Glutathione is an antioxidant substance in the body, and has been reported to show physiological activities of whitening, anti-aging and hyperglycemia suppressive action based on the antioxidant action. In addition, since the content of glutathione decreases in cells such as T lymphocyte and the like in human showing decreased immune function (see non-patent document 1), supply of glutathione from the outside is considered to enhance the immune function.
However, glutathione shows decreased quality by influences of heat, oxygen, light and the like and, as a result, may cause an unpleasant odor like sulfur, a decreased content and the like in a preparation.
As a method of suppressing decrease of the quality of glutathione, a method including coating the surface of the particles of a glutathione powder (see patent documents 1 and 2), a method including adding cyclodextrin (see patent documents 1 and 3) and the like are known. However, these methods are problematic in that the operation is complicated, the effect is weak, and the like.
On the other hand, arginine is known as a synthesis substrate for protein, polyamine, nitric oxide and the like in the body. Reported physiological actions of arginine include an immunostimulating action (see non-patent document 2), a muscle-building action, a nitric oxide production promoting activity, a wound healing activity and the like.
Thus, both glutathione and arginine have various physiological actions including common physiological actions such as immunostimulating action and the like. Hence, simultaneously ingestion of glutathione and arginine is expected to afford not only an additive effect but also a synergistic effect of each of the physiological actions.
However, it has not been known that the coexistence of glutathione and arginine markedly decreases the quality of glutathione.    patent document 1: JP-A-5-176739    patent document 2: JP-A-2002-97153    patent document 3: JP-A-64-63342    non-patent document 1: “Pediatric Infectious Disease Journal” 1998, vol. 17, No. 3, p. 236-241    non-patent document 2: “Surgery”, 1990, vol. 108, No. 2, p. 331-337